Create AgeRange class for age ranges #2714

data-serving/reusable-data-service/data_service/model/age_range.py

@@ -0,0 +1,41 @@
+import dataclasses
+
+from data_service.model.document import Document
+from data_service.util.errors import ValidationError
+
+@dataclasses.dataclass
+class AgeRange(Document):
+    """I represent a numerical range within which a person's age lies (inclusive of both limits).
+    To avoid reidentifying people who have been anonymised by this
+    application, I will only tell you their age to within five years (unless they are infants)."""
+    lower: int = None
+    upper: int = None
+
+    def __post_init__(self):
+        """Massage the supplied lower and upper bounds to fit our requirements. That doesn't
+        preclude somebody changing the values after initialisation so please do remember to
+        validate() me."""
+        if self.lower is not None and self.lower != 0:
+            self.lower = (self.lower // 5) * 5 + 1
+        if self.upper is not None and self.upper != 1 and self.upper % 5 != 0:
+            self.upper = ((self.upper // 5) + 1) * 5
+
+    def validate(self):
+        """I must represent the range [0,1], or a range greater than five years, and must
+        have a positive lower bound and an upper bound below 121."""
+        if self.lower is None:
+            raise ValidationError("Age Range must have a lower bound")
+        if self.upper is None:
+            raise ValidationError("Age Range must have an upper bound")
+        if self.lower < 0:
+            raise ValidationError(f"Lower bound {self.lower} is below the minimum permissible 0")
+        if self.upper < 1:
+            raise ValidationError(f"Upper bound {self.upper} is below the minimum permissible 1")
+        if self.upper > 120:
+            raise ValidationError(f"Upper bound {self.upper} is above the maximum permissible 120")
+        # deal with the special case first
+        if self.lower == 0 and self.upper == 1:
+            return
+        if self.upper - self.lower < 4:
+            # remember range is inclusive of bounds so e.g. 1-5 is five years
+            raise ValidationError(f"Range [{self.lower}, {self.upper}] is too small")

data-serving/reusable-data-service/tests/test_age_range.py

@@ -0,0 +1,68 @@
+import pytest
+
+from data_service.model.age_range import AgeRange
+from data_service.util.errors import ValidationError
+
+from tests.util import does_not_raise
+
+
+def test_age_range_massages_input_to_match_buckets():
+    ages = AgeRange(2,6)
+    assert ages.lower == 1
+    assert ages.upper == 10
+
+
+def test_age_range_leaves_input_if_it_is_already_on_bucket_boundary():
+    ages = AgeRange(6, 10)
+    assert ages.lower == 6
+    assert ages.upper == 10
+
+
+def test_age_range_invalid_if_boundaries_are_None():
+    ages = AgeRange(None, None)
+    with pytest.raises(ValidationError):
+        ages.validate()
+    ages = AgeRange(None, 12)
+    with pytest.raises(ValidationError):
+        ages.validate()
+    ages = AgeRange(5, None)
+    with pytest.raises(ValidationError):
+        ages.validate()
+
+
+def test_age_range_invalid_if_lower_bound_negative():
+    ages = AgeRange(-12, 4)
+    with pytest.raises(ValidationError):
+        ages.validate()
+
+
+def test_age_range_invalid_if_upper_bound_negative():
+    ages = AgeRange(5, -27)
+    with pytest.raises(ValidationError):
+        ages.validate()
+
+
+def test_age_range_invalid_if_upper_bound_methuselan():
+    ages = AgeRange(15, 150)
+    with pytest.raises(ValidationError):
+        ages.validate()
+
+
+def test_age_range_invalid_if_gap_too_small():
+    ages = AgeRange(None, None)
+    ages.lower = 10
+    ages.upper = 11
+    with pytest.raises(ValidationError):
+        ages.validate()
+
+
+def test_age_range_ok_for_infants():
+    ages = AgeRange(0, 1)
+    with does_not_raise(ValidationError):
+        ages.validate()
+
+
+def test_age_range_ok_for_large_positive_range():
+    ages = AgeRange(30, 45)
+    with does_not_raise(ValidationError):
+        ages.validate()

data-serving/reusable-data-service/tests/test_geojson_model.py

@@ -1,18 +1,9 @@
 import pytest
 
-from contextlib import contextmanager
-
 from data_service.model.geojson import Point, Feature
 from data_service.util.errors import ValidationError
 
-
-@contextmanager
-def does_not_raise(exception):
-    try:
-        yield
-    except exception:
-        raise pytest.fail(f"Exception {exception} expected not to be raised")
-
+from tests.util import does_not_raise
 
 def test_point_needs_two_coordinates():
     p = Point()

data-serving/reusable-data-service/tests/util.py

@@ -0,0 +1,10 @@
+import pytest
+
+from contextlib import contextmanager
+
+@contextmanager
+def does_not_raise(exception):
+    try:
+        yield
+    except exception:
+        raise pytest.fail(f"Exception {exception} expected not to be raised")